Peripheral white blood cell alterations in early labor.

The peripheral blood counts of 101 pregnant women in very early labor and 41 nonpregnant controls were compared through automated total and differential blood count techniques. There were profound quantitative changes in the peripheral bloods of the pregnant women. These included, in association with pregnancy, increases in the absolute number (per ml) of total white cell counts (p less than 0.0005), segmented neutrophils (p less than 0.0005), band neutrophils (p less than 0.0005), and monocytes (p less than 0.0005). In contrast, there was a significant decrease in the absolute number (per ml) of peripheral lymphocytes in pregnancy (p less than 0.05) and a significantly larger proportion of bloods from pregnant women had less than 10(6) lymphocytes per ml (p less than 0.0005). The percentage of segmented neutrophils increased significantly during pregnancy (p less than 0.0005) as did band neutrophils (p less than 0.0005). We also noted a significant decrease in the percentages of peripheral lymphocytes (p less than 0.0005). In contrast, there were no significant differences in the percentages of monocytes between pregnant women and nonpregnant controls. The increase in the absolute number of monocytes and the decrease in the absolute number of lymphocytes led to a significant decrease in lymphocyte-monocyte ratio (p less than 0.0005) during pregnancy. It is concluded that the maternal peripheral blood changes in late pregnancy may reflect immune changes required for the immune adaption between fetus and mother-host.